Process for sweetening hydrocarbon oil



sin I {3 i Shell l Development j,.0omp

am a corporatior of Delaware s relates to he reatment offliydrothe removal of eom'p'ouri'd 'and: particularly to the ddetor trat a menace" i nt petmigfirirs a i I 'oggpe;

-- iGd'soline refined the which this process I marked tendency to; discolor and'getcloudy when exposed to' 'the smn gne. preperty creole:- and re -instability is obj ectionable 'and detracts from thie commercial value oftheproducti 1 'I'hE- obj eat-of this' mvention is the 'sweetening' of hydzocarbon oilby an improved process-so that the product is bothhaieandi color-stable r {L'he-fso'uriodorr et -gasoline "is usually ascr bed to ebmpounii'efcontainingsulfur such as the mercap tans; 'These compounds' are usuallyjreinoved by theLfdoctor treatmentfl: which conslstsi ot ,trea'.t-- gasoline r certainisolutions containing 1 enemas:ansolutioiriofisodium'lpluinbitein so hydroxide. sodiunriiplumbihi actsi ito decompose the mercaptans present; some freeislfl for isradded in the-end: of: theTltreatmentitohssist ini'the precipitation f; the: insoluble lead 'sulfide's inrmfl ueAszthegprocess-is: Jusually: came out umcient sodiiimrplumbite s'olntion is-addedto: "gasoline to react; with the". sulfur-bearing hydrocarbons.

:eiiziI-mis'procs sin-1 this reactiom the'gasoline takes: :on ei greenishcolor. .sulfunisithen'addedtothe-mix turej-towprecipitate; -.the. "lead-.2: this:::sulf'11r is being addeetilithe coloniofli thein ixture tchaiiges to ellowgredgz deepredivreddishz-brown and then to a very cloudy black-red, or brown. At this point, with a very little addition of sulfur, the lead sulfide break occurs which consists of the sudden precipitation of the lead sulfide, leaving the gasoline clear and practically colorless. It isalways necessary to add sulfur a little inexcessof that just needed to combine with the lead, in order to start the precipitation Consequently,-;there is always a little free sulfur dissolved in the gasoline after'the treatment is completed, and thisis one; of the causes of hazeand color-instability in gasoline so treated. The process of my invention consists in treating the gasoline with sodium plumbite as usual but with insufiicient sulfur to precipitate out the lead. The gasoline, plumbite, and sulfur are mixed in amount used is less than the amount needed to 4 precipitate the lead. This is in distinct contrast aiaplicsfion septemberze; 1939? 5 eriahdio. 185,312m 1 r preveaiint'hasa very "less expensive. any manner whereby intimate contact between-- any, San Francisco,

with 'the'regular'process, the essence ofwhich' is the additi" or a slighteigcess df'sulfu rt preiliitat rfiti C010 mixture-is usedo ihd-ieate the quantity-of 'sulfu1- to be added-andthe point at'which this addition is to'cease. As wasibeforecmentioned, the-gasoline, ,after beingmixed with the. plumbite,v usually takes qnagreenish color; As the sulfur is, added this colorlchanges to. yellow, red; reddishbrown,

or in some ca ses brown. The addition of sulphur ybe. to rie lv at. he esta esrreferahlr at apoint where the oil is transpare d a deep; 'ed -ogbrown col 'r,-.m;'lhelpoiiit addition of sulfu -is stopped is easily detenmn d other niecliar-iicahor" 1 In this process I prefer to use a clay treatment. The treaterto which the gasoline mixture is passed is possible so that intimate mixing of the clay and oil is obtained. The. clay oil mixture is then wherebythe clay is removed. Theamount of clay necessary depends onthe character of the gasoline and the, amount of sulfur which has been 35 may be of any type wherein thorough agitation 1 sent through a filter press or other apparatus added. Asa rule, this amount is small, it being A very seldom necessary to add more than 2.0% of clay. to yield a product of satisfactory color.

sults. Though not as eflicient as the clay treatment;. it has the advantage of being simpler and The gasoline resulting from the'clay or, water treatment issweet in odor, has a colorless appear- I have also used water washing with very good reance and is hazeand color-stable to a marked degree in the sunlight. This product is generally I not negative to the doctor test but slightly -positive. However, the gasoline is sweet; in Jodor this gasoline I have compared it with samples of fully sweetened, first-cut pressuregasoline treated in the usual manner. These tests were made in four ounce clear glass bottles, the samples being exposed to bright sunlight and examined for haze and color at stated intervals. The color change is indicated by the Saybolt color scale;

Haze stability Appearance are; Gasoline Start v lliour 3 hours 5 hours" Regular; process fully S ligbtly sweetened Clear Clean.-- hazy Cloudy. Sweetened by my I metho H do -Gle ar- Clear.

- vE0101 Stability 1 y Q I Color afterlhour 35110 1113 5 hours (T1010 iTo '17 a cloudy). cloudy). ,2a'+ 218+ 16 Erom the above it willbe noted that this product is perfectlyhaze stable tome-tests and that the color of this productafter four or five hours? ex osu e ebpu .1 3 h t Qi ar gasoline after onehour; =1.

Sometimes :it is not-practical. or desirable to treat the red gasoline from the sweetening process dl flec ily withtheflclay. In this case the: mixture may be run into a storage tank and allowed'to stand. Many of the gasolines, on so a standing for sometime .willchange from a red or brown to a very light bro mi or yellow color at the same time depositing a'precipitate of lead sulfide in the bottom of the tank When it isdesired to treat this gasoline the lighter colored liquidmay be drawn can-o the precipitate and passed to-the clay mixer. .Intreating this oil, considerably less clay is necessary than when the liquid comes direct from the sweetening process.

Some gasolines are only slightly sour and require very little sweetening treatment. In such cases the addition of sulfur is often unnecessary. When these gasolines are treated by my process it: is only necessary to'treat them with small amounts of the sodium plumbiteand then pass directly to the clay treater without any addition of sulfur. Upon removal of the clay the product is clear, colorless and sweet and very stable to sunlight.

By way of illustratingmy process, I have described thtreatmentof gasoline. However, I do not limit myself to this particular product, my method being applicable to the treatment of any hydrocarbon oil that can be refined and sweetened by the doctor process as generally employed in the petroleum-industry.

I claim as my invention:

(v1: The process for sweetening hydrocarbon oils comprising treating the oils with sodium plumbite, adding sulfur in an. amount just short of that which would cause precipitation of lead sulfide but sufiicient to produce oils of sweet odor, and subsequently treating-them to remove the color without further addition of sulfur; 2; 'Ihezprocess'for sweetening gasoline or kerosene; comprising treating it with sodium plumbite, adding sulfur'in an amount just short of that which would cause -precipitation of lead sulfide but'sufficient to produce oils ofsweet odor and subsequently treating. it to remove the color without further addition of sulfur.

. i-3.;The :processwfor sweetening gasolinev comprising treating it with sodium plumbite,-gradually; adding sulfur till the color of the gasoline mixture: becomes re'd or-brown but in an amount justshort of that which would cause precipitation of lead sulfide andsubsequently treating it with clay'toremove the color .withoutfurther addition ofwsulfu'rpxy q 4. 'I'heItprocessfor sweetening a mineral oil distillate coinprising :1 mixing. said distillate with sodium plumbite solution, adding to theresultant 

